Railway signaling apparatus



Oct, 6, 1936.

P. H. CRAGO RAILWAY SIGNALING APPARATUS Filed July 50, 1935 I QB] R] BTR (Z0350 M/OSTROKE F/VO POLL DOW/V INVENTOR rawl/I7. Urayq.

H18 ATTORNEY Patented Oct. 6, 1936 UNITED STATES PATENT OFFEQE RAILWAY SIGNALING APPARATUS Application July 30, 1935, Serial No. 33,839

8 Claims.

My invention relates to railway signaling apparatus, but more particularly to circuits and apparatus for controlling a highway signal at the intersection of a highway and a stretch of railway track.

An object of my invention is to provide track circuits at the intersection employed in part to control the signal, and each having all the advantages of a track circuit employing the wellknown primary and secondary track relay combination without the expense of providing the secondary relay of such a combination.

I obtain these advantages by giving each of the magnets of the interlocking relay, employed in the immediate control of the highway signal, the same characteristics as those of the secondary relay of a primary-secondary track relay combination, and by then employing them as secondary relays.

In the accompanying drawing, Figs. 1, 1 and 2 are diagrammatic views illustrating three forms of circuits and apparatus, each embodying my invention.

Similar reference characters refer to similar parts in each of the views.

Referring first to Fig. 1, the reference characters l and la designate the rails of a stretch of railway track, which rails are divided by insulate-d joints 2 to form two track sections designated A and B, respectively, with. their adjoining ends located at a highway intersection designated H. Each track section is provided with a track circuit including a source of current 3 connected across the rails at one end of the section, and a track relay designated TR having a prefix corresponding to the section to which it belongs and connected across the rails I and la at the other end of the section. The highway signal 8- may be of any suitable type and is under the immediate control of the magnets AI and BI of the interlocking relay IR. This relay may be of any of the well-known types, such as, for example, the type disclosed in Patent No. 1,799,629, issued to William K. Lockhart and Thomas J. OMeare, April 7, 1931. Each of the magnets AI and BI is normally held energized over a circuit including the front contact of the associated track relay, in series with a resistor R2. Each of the magnets Al and BI when picked up excludes at its back contact 12 a portion of the winding of the associated track relay from the track circuit and in addition makes it necessary for all track circuit current to pass through the associated resistor RI. This is one of the usual expedients emplayed in a primary-secondary track relay combination to increase the release sensitivity of the primary or track relay. Another expedient is to use the conventional form of track relay such as TR shown in Fig. 1 in which case each of the magnets Al and Bi when picked up includes a resistor such as R! in circuit with its associated relay TR to increase its release sensitivity.

Each of the magnets Al and BI at its back contact 83 controls. the signal S in the usual manner. It may be well to explain at this time that the back contacts ll and ii! of magnets AI and Bi are closed when they are the first to be released by the relay IR, but become latched in the open position if the contacts H and I3 associated with the other magnet of relay IR were first to be released. The back contact E2 of either magnet of this relay always closes when its magnet becomes deenergized that is, each contact I2 is closed at mid stroke and full down positions; while the front contact ll of either magnet always closes when its magnet becomes energized.

I will now assume that a train moving toward the highway enters section A, thereby shunting current away from the track relay ATR. When relay ATR releases, its front contact opens the circuit for magnet Al of relay IR. When magnet AI releases, its back contact I I places a shunt around the associated resistor R2, thus preparing a pick-up circuit for magnet All. Also, back contact l2, by closing, includes the formerly excluded portion of the winding of relay ATR in the track circuit, thereby preparing the pick-up circuit for relay ATR. Furthermore, magnet Al closes at back contact l3 a circuit through signal S, which signal accordingly operates as long as the section remains occupied.

When the train enters section B, track relay B'IR also releases and at its front contact opens the circuit of magnet Bl. When magnet BI releases, its back contact l2 closes and includes the entire winding of relay BTR in its track circuit, thereby preparing for pick up of this relay when the train vacates section B. The back contacts H and E3 of magnet Bl, however, do not close at this time as they have been latched in the open position by the prior release of magnet AI.

As: the train vacates section A, the track relay ATR again picks up and at its front contact reestablishes a circuit for magnet Al. This circuit includes the closed back contact I! of relay Al and the associated resistor R2, in multiple. After a slight delay, relay Al picks up, opening back contact I l to include the associated resistor R2 in its holding circuit, and at back contact 12 again excludes a portion of the winding of relay ATR. from the track circuit to increase the release sensitivity of the relay ATR. At back contact [3, relay Al opens the circuit of signal S to discontinue the warning at the crossing.

Since, as previously explained, back contact ll of the last released magnet (magnet Bl in this instance) is not closed, the associated resistor R2 is not shunted and therefore when the train vacates section B and relay BTR. picks up, the current supplied to the winding of magnet BI is reduced by resistor R2 sufiiciently to retard the pick-up time of this magnet in such a manner as substantially to oifset the tendency for the pick-up to be accelerated due to the reduction of the air gap between the magnet armature and core resulting from the mechanical latching of the armature to hold contacts I l and I3 open, as previously explained.

Since the relationship between track relayv BTR and interlocking relay IR. is symmetrical with that existing between track relay AIR and relay IR, it will be apparent that the control of signal S will be the same irrespective of the direction from which a train approaches the intersection.

In Fig. 2, I have shown the circuits and apparatus of Fig. 1 modified by the addition of a connection between the front and back points of contact ll of magnets Al and BI. The front point of contact II is employed in order to overcome the tendency of resistor R2 to reduce the final level of energy in the windings of magnets AI and BI to an undesirable value. The operation will be the same as described for Fig. 1, except that when magnets AI and BI pick up, their front contacts II will again shunt out the associated resistors R2, thereby restoring the energy being supplied to the relay to the value used for initially picking it up from its fully released position.

In Fig. 2 I have also shown the signal S as being controlled through the medium of a repeater relay RE which is energized over flagman type front contacts [3 of magnets Al and B! to illustrate the form the invention will take when the current load of the signal S, or this signal plus other apparatus exceeds the capacity of the contacts available on the interlocking relay IR.

Although I have herein shown and described only three forms of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a stretch of track divided into two sections the adjoining ends of which are intersected by a highway, a signal for warning highway trafiic of an approaching train, a track circuit for each track section including a source of current and the winding of a track relay, a slow-acting interlocking relay for controlling said signal through the medium of either of said track relays and having two magnets, alternative pick-up circuits for each of the magnets each including a front contact of one of said track relays and one of each of said alternative circuits including a resistor, and a back contact associated with each magnet of said interlocking relay for at times excluding a portion of the winding of the associated track relay from its track circuit.

2. In combination with a stretch of railway track divided into two track sections both of which are intersected by a highway, a signal for controlling traflic over the highway, 21. first track relay associated with one of said sections for controlling said signal during trafiic movements in one direction, a second track relay associated with the other of said sections for controlling said signal during traffic movements in the opposite direction, an interlocking relay jointly controlled by said track relays and assisting said track relays in the control of said signal; a pickup circuit for each winding of said interlocking relay including a contact thereof and a resistor in multiple as well as a front contact of one of said track relays, said pick-up circuit being effective only when such winding is the first of the two to be deenergized; a second pick-up circuit for each winding of the interlocking relay including said resistor in series and a front contact of one of said track relays and efiective only when such winding is the last of the two to be deenergized; and circuits for controlling the release sensitivity of said track relays each including a back contact of said interlocking relay. 3. In combination with a stretch of railway track divided into two sections both intersected by a highway and each provided with a track circuit including a source of current and the winding of a track relay, a highway signal at the intersection, an interlocking relay for controlling the actuation of said signal while a train is approaching the intersection, said control being effective only until the section first entered is cleared by the train, a circuit for one winding of the interlocking relay including a front contact of the track relay for one of the sections, a circuit for the other winding of the interlocking relay including a front contact of the track relay for the other of the sections; a back contact on the interlocking relay for each winding thereof for at times increasing the release sensitivity of the associated track relay, and other contacts on said interlocking relay for controlling said signal.

4. In combination, a stretch of railway track intersected by a highway and formed into two track sections one on each side of the highway, a highway crossing signal located adjacent the intersection, a track circuit for each section including a track relay, an interlocking relay including a pair of magnets, a first pick-up circuit for each magnet including a full down contact of such magnet and a front contact of a particular one of said track relays, a second pickup circuit for each magnet including a resistor and the front contact of the particular track relay, and circuit means for controlling said signal and including a contact of each magnet of the interlocking relay.

5. In combination, a stretch of railway track intersected by a highway and formed into two track sections one on each side of the highway, a highway crossing signal located adjacent the intersection, a track circuit for each section in cluding a track relay, an interlocking relay including a pair of magnets, a normal energizing circuit for each magnet including a front contact of such magnet and a front contact of a particular one of said track relays, a first pickup circuit for each magnet including a full down contact of such magnet and the front contact of the particular track relay, a second pick-up circuit for each magnet including a resistor and the front contact of the particular track relay, and circuit means for controlling said signal and including a contact of each magnet of the interlocking relay.

6. In combination, a stretch of railway track intersected by a highway and formed into two track sections one on each side of the highway, a highway crossing signal located adjacent the intersection, a track circuit for each section including a track relay, an interlocking relay wherein the armature of the first deenergized winding of the relay in restoring to its fully released position prevents the armature of the second deenergized winding from restoring to its fully released position, circuit means for picking up each armature from either of its released positions and each of said circuit means including a front contact of a particular one of said track relays, means associated with each of said circuit means effective to maintain the pick-up time of the armature substantially the same for either released position, and other circuit means for controlling the signal and including a contact of each winding of the interlocking relay.

7. In combination, a stretch of railway track intersected by a highway and formed into two track sections one on each side of the highway, a highway crossing signal located adjacent the intersection, a track circuit for each section including a track relay, an interlocking relay including two windings and having a full down as well as a mid position for each of its armatures, an energizing circuit for each Winding including a front contact of a particular one of the track relays, said circuits each effective to pick up the armature of the winding within a fixed interval of time after the circuit for such winding is closed, means associated with each energizing circuit to retard the pick up of the armature of the associated winding from its mid position to efiect substantially the same fixed pick-up interval of time after the circuit is closed, and circuit means for controlling the signal and including a contact of each of said armatures.

8. In combination, a stretch of railway track intersected by a highway and formed into two track sections one on each side of the highway, a highway crossing signal located adjacent the intersection, a track circuit for each section including a track relay, an interlocking relay having two windings and interlocking mechanism such that the armature of either winding releases to a mid position when its winding is the last of the two to become deenergized, an energizing circuit means for each winding controlled by a particular one of the track relays and made effective by a contact of the armature of the winding when fully released to supply current of a greater value than that which will be supplied when the armature is in its mid position and other circuit means for controlling said signal and including contacts of the interlocking relay.

PAUL H. CRAGO. 

